Rotary electric machines for converting electrical power into rotary force (torque) and/or rotary power into electrical power have been widely used for wide industrial fields.
Such rotary electric machines are made up of a rotor and a stator located relative thereto. The stator consists of a stator core and a stator coil assembled in the stator core for creating a rotating magnetic field when energized.
In these rotary electric machines, in order to improve assembly of the stator coil into the stator core, some types of rotary electric machines including a specific stator are proposed; this specific stator consists of a stator core assembly made up of a plurality of core segments. Such a specific stator is for example disclosed in Japanese Patent Publication No. 3604326.
The stator disclosed in the Japanese Patent Publication includes a ring stator core assembly consisting of a plurality of fan-shaped yoke pieces (core segments). The yoke pieces are annually arranged such that one side end of each yoke piece and one side end of another yoke piece adjacent thereto in the annular direction are overlapped with each other in an axial direction of the whole of the yoke pieces. Each of the yoke pieces is formed at its inner side with a plurality of teeth; these teeth provide slots therebetween.
The ring stator also consists of a preformed ring stator coil assembled in the stator core. The stator coil is formed with a plurality of radial windows therethrough.
When the yoke pieces and the stator coil are assembled to each other to provide the stator, the yoke pieces are arranged around the outer circumference of the stator coil.
Next, the yoke pieces are moved toward the stator coil so that the teeth are inserted in the radial windows, respectively.
Thereafter, the overlapped sides of the yoke pieces are joined to each other to thereby provide the stator core assembly and stator.
However, in such stators formed in such a manner that the yoke pieces are moved toward the stator coil so that the teeth are respectively inserted in the radial windows, the assembling of the yoke pieces into the stator coil may cause damage to the stator coil.
Specifically, before the yoke pieces are moved toward the stator coil, one side end of each yoke piece and one side end of another yoke piece adjacent thereto in the annular direction have been overlapped with each other.
For this reason, when the yoke pieces are moved toward the stator coil, it is necessary to hold the yoke pieces such that the overlapped sides of the adjacent yoke pieces are pressed in the axial direction. This holding however may cause the yoke pieces to swing in the circumferential direction when the yoke pieces are moved toward the stator coil. This may cause the teeth to hit on the stator coil so that the stator coil may become damaged.